Experimental study of temperature & pressure effects on high-porosity PZT materials

This work was motivated by the quest for substitute piezoceramic materials with similarly low acoustic impedance as lead metaniobate, but significantly higher electromechanical coupling. We investigated the performance of two PZT-based materials with engineered porosity, namely Pz31 and Pz36 developed by Meggitt A/S, that offer comparable acoustic impedance to lead metaniobate, yet high kt approaching that of regular PZT materials. In particular, we considered operating environments where the piezoceramic is subjected to high temperature and high pressure (up to 175°C and 20,000 psi). The objective is to characterize the electromechanical behavior of the Pz materials under such conditions. The test systems and procedures are described. The experimental results show that the Pz materials perform consistently well at temperatures up to 175°C under normal pressure. However, both materials tend to depole by pressure cycling up to 15,000 psi. Post-mortem analyses have been carried out to ascertain the causes of depoling and suggest potential solutions.